Last reviewed: February 8, 2021
- Routine preoperative cervical preparation is recommended before dilatation and evacuation (D&E).
- Osmotic dilators, misoprostol and mifepristone are options for cervical preparation. The choice depends on availability, expense, gestational age and timing of the procedure.
Strength of recommendation: Strong
Quality of evidence: High
Cervical preparation prior to D&E reduces the risk of procedure-related complications (Fox & Krajewski, 2014; Peterson, Berry, Grace, & Gulbranson, 1983). There is limited data to suggest the best method of cervical preparation before D&E because the trials that exist have heterogeneous comparisons, proxy outcomes for adverse events, small sample sizes, and include few women with pregnancies over 20 weeks (Ralph & Shulman, 2019). Available trials typically show differences in cervical dilation or procedure times, however they do not include enough participants to show differences in rare but more serious outcomes such as cervical or uterine injuries or inability to complete the procedure (Newmann et al., 2010). Choice of method of cervical preparation is often limited by supply availability, especially in low-resource settings.
6-24 hours prior to procedure
Synthetic osmotic dilators may be used the day of the D&E
400mcg buccally or vaginally 3 hours prior to procedure
May be used as a single agent up to 18 weeks, very limited data to support use as a single agent over 18-20 weeks
May be combined with osmotic dilators or mifepristone
May be repeated as needed
200mg orally 24-48 hours prior to procedure
Limited data support use as a single agent up to 18 weeks
Often used prior to misoprostol
Numerous cohort studies have demonstrated that osmotic dilators are safe, effective and do not increase infectious morbidity (Bryman, Granberg, & Norström, 1988; Fox & Krajewski, 2014; Jonasson, Larsson, Bygdeman, & Forsum, 1989; Peterson et al., 1983). A Cochrane meta-analysis of cervical preparation before D&E between 14-24 weeks gestation showed that overnight osmotic dilators provide better cervical dilation when compared to prostaglandins, and decreased procedure time between 13-16 weeks gestation (Newmann et al., 2010). In one randomized controlled trial, synthetic dilators and laminaria worked equally well (Newmann et al., 2014). Decisions about the number and timing of dilators to place should be individualized and take into consideration the type of dilator and its size, the gestational age of the pregnancy, parity and cervical compliance, and the provider’s experience (Fox & Krajewski, 2014; Newmann, Dalve-Endres, & Drey, 2008).
Women experience pain both during dilator placement and overnight as dilators expand in the cervix; pain typically peaks two hours after dilator placement (Creinin et al., 2020; Liu & Flink-Bochacki, 2020; Nagendra et al., 2020). Pain experience does not differ by type of dilator used (Liu & Flink-Bochacki, 2020). In randomized controlled trials, administration of paracervical block prior to osmotic dilator insertion eases the discomfort of dilator placement for women (Soon et al., 2017) and use of non-steroidal anti-inflammatory medications (NSAIDs) decreases the experience of cramping pain for the hours following insertion until procedure, compared to oral opioids (Nagendra et al., 2020).
Misoprostol is inexpensive, safe (Nucatola, Roth, Saulsberry, & Gatter, 2008), and more readily available than osmotic dilators in many low-resource settings. Misoprostol may be used alone for cervical preparation prior to D&E up to 20 weeks gestation (Fox & Krajewski, 2014; O’Connell, Jones, Lichtenberg, & Paul, 2008; Shakir-Reese et al., 2019); there is limited data to support use of misoprostol as a single agent after 18 weeks (Maurer, Jacobson, & Turok, 2013; Shakir-Reese et al., 2019). In studies comparing osmotic dilators to misoprostol, dilators provided more cervical dilation (Goldberg et al., 2005; Sagiv et al., 2015; Shakir-Reese et al., 2019). However, women who received misoprostol for cervical preparation were able to have their procedures safely completed on the same day (Bartz et al., 2013; Goldberg et al., 2005; Sagiv et al., 2015), and women often preferred misoprostol to dilators (Goldberg et al., 2005). Misoprostol may be given to women with a prior cesarean delivery, as uterine rupture is rare (Fox & Krajewski, 2014). A study of same-day use of osmotic dilators plus adjunctive 400mcg misoprostol versus only misoprostol 4-6 hours prior to D&E up to 20 weeks gestation resulted in comparable D&E procedure times between the two groups, although the osmotic dilator plus misoprostol group had significantly greater dilation at D&E initiation (Shakir-Reese et al., 2019). Because placing osmotic dilators takes more time than was saved by having greater baseline dilation, the overall procedure time (placing osmotic dilators plus D&E procedure) was longer by 3.2 minutes in the osmotic dilator plus misoprostol group.
Misoprostol plus osmotic dilators
A meta-analysis of three randomized controlled trials of misoprostol versus placebo added to overnight laminaria at gestational ages greater than 16 weeks demonstrated a tendency toward improved baseline cervical dilation and decreased operating time by an average of 1.5 minutes (Cahill, Henkel, Shaw & Shaw, 2019); however, neither finding was statistically significant in the weighted analysis, with significant heterogeneity between studies. Overall complication rates were low in all three studies and did not differ significantly by treatment group (Cahill, Henkel, Shaw & Shaw, 2019: Drey et al., 2013; Edelman, Buckmaster, Goetsch, Nichols, & Jensen, 2006; Goldberg et al., 2015). In all studies, side effects were greater among women using misoprostol.
One small prospective randomized trial has examined adding misoprostol to dilators for same-day D&E (Borras et al., 2016). Investigators ended this study early due to an unexpectedly high rate of complications—specifically serious cervical lacerations—in women over 19 weeks gestation who received dilators alone for cervical preparation.
One randomized trial of 50 women between 14-16 weeks gestation compared mifepristone as a single agent to dilators, both administered the day prior to the abortion procedure (Borgatta et al., 2012). Women who had cervical preparation with osmotic dilators had a slightly shorter procedure time and greater dilation compared to women given mifepristone, but women had less pain with mifepristone and strongly preferred it. A second randomized trial of 49 women between 15-18 weeks gestation with similar design (single-agent mifepristone compared with osmotic dilators the day prior to procedure) found no difference in procedure time between the two treatment groups (Paris, et al, 2019). When asked, most women who had the mifepristone preferred it, while most who had osmotic dilators reported that they would have preferred a different treatment option for cervical priming.
In studies examining the use of mifepristone in combination with misoprostol, same-day administration of mifepristone plus misoprostol is no better than misoprostol alone (Casey, Ye, Perritt, Moreno-Ruiz, & Reeves, 2016), and while administration of mifepristone 2 days prior to misoprostol resulted in improved cervical dilation in one study, the rate of preprocedure fetal expulsions was also increased (Carbonell et al., 2007). When compared to overnight dilators plus misoprostol, mifepristone administered the day prior to the abortion plus same-day misoprostol is less effective (Shaw et al., 2017).
Mifepristone plus osmotic dilators
Two randomized trials have assessed the addition of mifepristone when women received overnight osmotic dilators plus misoprostol for cervical preparation; neither study showed additional benefit with mifepristone (Shaw et al., 2017; Shaw et al., 2015). A third randomized trial compared overnight dilators alone, overnight dilators plus misoprostol, and overnight dilators plus mifepristone (Goldberg et al., 2015), and found that procedure times were no different between the three groups, although providers reported that procedures between 19-24 weeks gestation were easier in the dilators plus mifepristone group.
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